Ann Forsyth, J. Michael Oakes and Kathryn H. Schmitz
The Twin Cities Walking Study measured the associations of built environment versus socioeconomic and psychosocial variables with total physical activity and walking for 716 adults.
This article reports on the test–retest reliability of the survey portion of the study. To test the reliability of the study measures, 158 respondents completed measures twice within 1 to 4 weeks. Agreement between participants’ responses was measured using Pearson r and Spearman rho, and kappa statistics.
Demographic questions are highly reliable (R > .8). Questions about environmental and social features are typically less reliable (rho range = 0.42– 0.91). Reliability of the International Physical Activity Questionnaire (last 7 days version) was low (rho = 0.15 for total activity).
Much of the survey has acceptable-to-good reliability. The low test–retest reliability points to potential limitations of using a single administration of the IPAQ to characterize habitual physical activity. Implications for sound inference are accordingly complicated.
John R. Sirard, Ann Forsyth, J. Michael Oakes and Kathryn H. Schmitz
The purpose of this study was to determine 1) the test-retest reliability of adult accelerometer-measured physical activity, and 2) how data processing decisions affect physical activity levels and test-retest reliability.
143 people wore the ActiGraph accelerometer for 2 7-day periods, 1 to 4 weeks apart. Five algorithms, varying nonwear criteria (20 vs. 60 min of 0 counts) and minimum wear requirements (6 vs. 10 hrs/day for ≥ 4 days) and a separate algorithm requiring ≥ 3 counts per min and ≥ 2 hours per day, were used to process the accelerometer data.
Processing the accelerometer data with different algorithms resulted in different levels of counts per day, sedentary, and moderate-to-vigorous physical activity. Reliability correlations were very good to excellent (ICC = 0.70−0.90) for almost all algorithms and there were no significant differences between physical activity measures at Time 1 and Time 2.
This paper presents the first assessment of test-retest reliability of the Actigraph over separate administrations in free-living subjects. The ActiGraph was highly reliable in measuring activity over a 7-day period in natural settings but data were sensitive to the algorithms used to process them.